Right now, cosmopolitan uses Linux Landlock ABI version 2 on Linux,
meaning that the polyfill for unveil() cannot restrict operations such
as truncate() (a limitation of Landlock's ABI from then). This means
that to restrict truncation operations Cosmopolitan instead has to ban
the syscall through a SECCOMP BPF filter, meaning that completely
legitimate truncate() calls are blocked
However, the newest version of the Landlock ABI (version 3) introduced
in Linux 6.2, released in February 2023, implements support for controlling truncation
operations. As such, the previous SECCOMP BPF truncate() filtering is
no longer needed when the new ABI is available
This patch implements unveil truncate support for Linux Landlock ABI
version 3
The C standard states that, in the context of an x conversion
specifier given to scanf:
> Matches an optionally signed hexadecimal integer, whose format is
> the same as expected for the subject sequence of the strtoul
> function with the value 16 for the base argument.
- C standard, 7.23.6.2.11. The fscanf function
Cosmopolitan fails to do this, as 0 should be parsed as a 0 by such an
invocation of strtoul. Instead, cosmopolitan errors out as though such
input is invalid, which is wrong.
This means that a program such as this:
#include <stdio.h>
#undef NDEBUG
#include <assert.h>
int main()
{
int v = 0;
assert(sscanf("0", "%x", &v) == 1);
}
will not run correctly on cosmpolitan, instead failing the assertion.
This patch fixes this, along with the associated GitHub issue,
https://github.com/jart/cosmopolitan/issues/778
The C standard, when defining field width and precision, never gives
any limit on the values used for them (except, I believe, that they
fit within an int). In other words, if the user gives a field width of
32145 and a precision of 9218, the implementation has to handle these
values correctly. However, when such kinds of high numbers are used
with integer conversions, cosmopolitan is limited by an internal
buffer size of 144, which means precisions and field widths have to
fit within this, which violates the standard.
This means that for example, the following program:
#include <stdio.h>
#include <string.h>
int main()
{
char buf2[512] = {};
int i = snprintf(buf2, sizeof(buf2), "%.9999u", 10);
printf("%d %zu\n", i, strlen(buf2));
}
would, instead of printing "9999 511" (the correct output), instead
print "144 144" under cosmopolitan.
This patch fixes this.
The C standard states:
> The fprintf function returns the number of characters transmitted,
> or a negative value if an output or encoding error occurred or if
> the implementation does not support a specified width length
> modifier.
- C Standard, 7.23.6.1.15. The fprintf function
However, cosmopolitan fails to return a negative value in the case of
an output error, meaning that a program such as:
#include <stdio.h>
int main()
{
FILE *fp = fopen("/dev/full", "w");
setbuf(fp, NULL);
printf("fprintf: %d\n", fprintf(fp, "test\n"));
printf("fflush: %d\n", fflush(fp));
}
will, under cosmopolitan, print that no error occured in either of the
calls to fprintf and fflush.
This patch fixes this, along with the associated GitHub issue,
https://github.com/jart/cosmopolitan/issues/784
_PFLINK is supposed to automatically pull in required functions for
specific conversion specifiers. However, it fails to do so for the F,
G and E conversion specifiers.
This means that, for example, the following program:
#include <stdio.h>
int main()
{
printf("%F %G %E\n", .0, .0, .0);
}
fails to run correctly, printing "? ? ?" instead of
"0.000000 0 0.000000E+00".
This patch fixes this.
The C standard states:
> Unless explicitly stated otherwise, the functions described in this
> subclause order two wide characters the same way as two integers of
> the underlying integer type designated by wchar_t.
>
> [...]
>
> The wcscmp function returns an integer greater than, equal to, or
> less than zero, accordingly as the wide string pointed to by s1 is
> greater than, equal to, or less than the wide string pointed to by
> s2.
>
> [...]
>
> The wcsncmp function returns an integer greater than, equal to, or
> less than zero, accordingly as the possibly null-terminated array
> pointed to by s1 is greater than, equal to, or less than the
> possibly null-terminated array pointed to by s2.
- C Standard, 7.31.4.4. Wide string comparison functions
Cosmopolitan fails to obey this in cases where the difference between
two wide characters is larger than WCHAR_MAX.
This means that, for example, the following program:
#include <stdio.h>
#include <wchar.h>
#include <limits.h>
int main()
{
wchar_t str1[] = { WCHAR_MIN, L'\0' };
wchar_t str2[] = { WCHAR_MAX, L'\0' };
printf("%d\n", wcscmp(str1, str2));
printf("%d\n", wcsncmp(str1, str2, 2));
}
will print `1` twice, instead of the negative numbers mandated by the
standard (as WCHAR_MIN is less than WCHAR_MAX)
This patch fixes this, along with the associated Github issue,
https://github.com/jart/cosmopolitan/issues/783
The C standard states that, within the context of a printf-family
function, when specifying the precision of a conversion specification:
> A negative precision argument is taken as if the precision were
> omitted.
- Quoth the C Standard, 7.23.6.1. The fprintf function
Cosmopolitan instead treated negative precision arguments as
though they had a value of 0, which was non-conforming. This
change fixes that. Another issue we found relates to:
> For o conversion, it increases the precision, if and only if
> necessary, to force the first digit of the result to be a zero (if
> the value and precision are both 0, a single 0 is printed).
- Quoth the C standard, 7.23.6.1.6. The fprintf function
When printing numbers in their alternative form, with a precision and
with a conversion specifier of o (octal), Cosmopolitan wasn't following
the standard in two ways:
1. When printing a value with a precision that results in 0-padding,
cosmopolitan would still add an extra 0 even though this should be
done "if and only if necessary"
2. When printing a value of 0 with a precision of 0, nothing is
printed, even though the standard specifically states that a single
0 is printed in this case
This change fixes those issues too. Furthermore, regression tests have
been introduced to ensure Cosmopolitan continues to be conformant
going forward.
Fixes#774Fixes#782Fixes#789
Cosmopolitan now conforms to the C Standard 7.8.1 specification
of the PRI and SCN macros, because this change fixes a bug where
the FAST16 ones were incorrectly using the %hd specifier.
The standard states that, when the # flag is used:
> The result is converted to an "alternative form". [...] For x (or X)
conversion, a nonzero result has 0x (or 0X) prefixed to it.
- C standard, 7.23.6.1. The fprintf function
cosmopolitan fails to use the correct alternative form (0X) when the X
conversion specifier is used, instead using 0x, which is not
capitalized.
This patch fixes this, along with the several tests that test for the
wrong behavior.
The C standard states, for conversions using the d, i, b, B, o, u, x or X conversion specifiers:
> The precision specifies the minimum number of digits to appear; if
> the value being converted can be represented in fewer digits, it is
> expanded with leading zeros.
- C standard, 7.23.6.1. The fprintf function
However, cosmopolitan currently suppresses the addition of leading
zeros when the minus flag is set. This is not reflected by anything
within the C standard, meaning that behavior is incorrect.
This patch fixes this.
* Implement S conversion specifier for printf-related functions
POSIX specifies that a conversion specifier of S must be interpreted
the same way as %ls. This patch implements this.
* clang-format
---------
Co-authored-by: Gavin Hayes <gavin@computoid.com>
Python triggered the undefined behavior previously since it appears to
be posting to a semaphore owned by a different process that wasn't set
to process shared mode. The performance loss to process shared futexes
is so low and semaphores are generally used for this purpose, so it'll
be much simpler to simply not impose undefined behavior here.
- Improve compatibility with Blink virtual machine
- Add non-POSIX APIs for joining threads and signal masks
- Never ever use anything except 32-bit integers for atomics
- Add some `#undef` statements to workaround `ctags` problems
This change adds a double linked list of threads, so that pthread_exit()
will know when it should call exit() from an orphaned child. This change
also improves ftrace and strace logging.
- clock_nanosleep() is now much faster on OpenBSD and NetBSD
- Thread joining is now much faster on NetBSD
- FreeBSD timestamps are now more accurate
- Thread spawning now goes faster on XNU
- Clean up the clone() code
- Clean up sigaction() code
- Add a port scanner example
- Introduce a ParseCidr() API
- Clean up our futex abstraction code
- Fix a harmless integer overflow in ParseIp()
- Use kernel semaphores on NetBSD to make threads much faster
- Exhaustively document cancellation points
- Rename SIGCANCEL to SIGTHR just like BSDs
- Further improve POSIX thread cancellations
- Ensure asynchronous cancellations work correctly
- Elevate the quality of getrandom() and getentropy()
- Make futexes cancel correctly on OpenBSD 6.x and 7.x
- Add reboot.com and shutdown.com to examples directory
- Remove underscore prefix from awesome timespec_*() APIs
- Create assertions that help verify our cancellation points
- Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)
This change makes some miracle modifications to the System Five system
call support, which lets us have safe, correct, and atomic handling of
thread cancellations. It all turned out to be cheaper than anticipated
because it wasn't necessary to modify the system call veneers. We were
able to encode the cancellability of each system call into the magnums
found in libc/sysv/syscalls.sh. Since cancellations are so waq, we are
also supporting a lovely Musl Libc mask feature for raising ECANCELED.
All tests pass now under WSL2. They should pass under WSL1 too, but only
WSL2 is integrated into the test fleet right now. This change also fills
in some gaps in the error numbers.
Fixes#665
